Corn is a widely studied and used plant, such as starch is made from corn kernels, and an active ingredient has recently been extracted from corn silk (Korean Patent Registration No. 10-1535835). However, when certain products are manufactured using corn, by-products thereof are generated, and it is often difficult to treat them.
For example, when corn starch is produced, corn steep liquor (CSL), and a corn germ portion and pericarp (bran), which are removed during extraction, are generated as by-products. In a liquid in which the immersion of raw materials has been completed, most of the soluble materials in corn are eluted, insoluble materials are partially extracted by cleavage and/or modification, and a large amount of lactic acid fermented by the eluted saccharides is contained. According to a report, the immersion-completed liquid is concentrated into CSL, and the liquid contains a large amount of carbohydrates, amino acids, peptides, vitamins, essential minerals, and phytic acid, which is known as an antioxidant of natural plants, and thus CSL is used as an organic nitrogen source with excellent nutrients in the fermentation industry and a part of it is used for feed. However, since CSL is present in a liquid phase having a very high viscosity, it is inconvenient in handling, and although a part of CSL is used as a medium for fermentation and a feedstuff, in most corn starch factories, a large amount of produced CSL is discharged into the sea at high cost due to a high chemical oxygen demand (COD) load caused when discharged as wastewater. However, the disposal of CSL has become a serious problem due to a complete ban by legal sanctions since 2016.
In addition, in the case of corn pericarp among by-products generated when starch is prepared from corn, it has been reported that phytosterol, which lowers cholesterol levels, is contained in oil components of the corn pericarp, and the content of arabinoxylan in corn pericarp and the structure, properties, and efficacy of corn pericarp have also been reported. However, research on CSL, which is a by-product produced when corn starch is prepared, is lacking, and this is especially true for research on polysaccharides contained in CSL.
Meanwhile, macrophages are cells which secrete various cytokines and regulate immune conditions during a process of engulfing and digesting microorganisms or foreign matter, and play a vital role in immune responses against antigens, and macrophages are involved in antigen presentation and a non-specific immune function of lymphocytes, and exhibit direct cytotoxicity on tumor cells. In addition, it is known that materials responding to toll-like receptors (TLRs) such as LPS or natural materials activate macrophages, leading to the proliferation of T cells and B cells, the activation of macrophages for phagocytosis, and the production of cytokines such as IL-1, IL-6, IL-12, and TNF-α, which are capable of regulating a secondary immune response such as a defense against microorganism infections. IL-6 and TNF-α, which are representative cytokines induced by macrophages, are known to play a pivotal role in the inflammatory response to bacterial infections and increase quantitatively in inflammatory lesions. IL-6 and IL-1 have been reported to be involved in the differentiation of T cells and B cells by cooperative action and have anti-cancer effects, and TNF-α has been known to have cytotoxic and antiviral actions on specific cancer cells and play an important role in various biological reactions occurring in acute and chronic inflammatory diseases. Meanwhile, IL-12, which is a cytokine that induces NK cell activation and Th1-type immune responses, is known to increase reactivity with foreign cells such as cancer cells.
As a result of having studied the use of by-products generated when corn starch is prepared, the inventors of the present invention discovered that specific polysaccharides separated from CSL were included in the CSL in a cleaved and modified state by sulfurous acid treated in a starch preparation process, and also identified its immuno-enhancing activity, thus completing the present invention based on the findings.